Box-type inverters are increasingly used in harsh environments like deserts and mountain areas with sandstorm, blizzard and the like. As shown in FIG. 1, a conventional air outlet 1 (which may also be an air inlet), is designed to face downwards for resisting water, and in this way, rainwater or accumulated snow is prevented from entering an air duct to a certain extent. In addition, in order to prevent dust from entering an interior of a box body, the air outlet 1 is provided with a dust filter 2, which can prevent dust from entering the interior of the box body as might occur during a sandstorm.
The structure of this air outlet of the conventional inverter has advantages, but also has disadvantages which are reflected in that:
1. The structure of the downward air outlet 1 direct hot air of the air outlet 1 downward, and if an air inlet is close to the air outlet, the hot air may be sucked into the air inlet, thus adversely affecting the heat dissipation performance of the entire inverter;
2. The air outlet 1 is provided with the dust filter 2 for resisting dust, which may increase the system resistance, reduce an air volume of a fan, and thus significantly affects the heat dissipation performance of the inverter, which could result in a too high temperature of a module, such that the heat dissipation requirements cannot be met.
For an air outlet of FIG. 2, water can easily enter an air duct or the inverter during a waterproof test when a water jet impacts upward at a certain angle from a lower position. Thus, this type of air outlet has a lower waterproof level and is poorly suited for an application requiring a high degree of waterproofness. To prevent such a water jet from entering an interior of the air duct, a non-planar or bent structure of this type of air outlet of FIG. 2 should be made to be very dense, which may greatly increase the air flow resistance, and the air flow out of the inverter is not smooth when entering this air outlet, thus the resistance is also increased. Even for an air outlet having a self-hanging louver structure, as shown in FIG. 3, the waterproof level is relatively low, and rain and snow may also enter the interior of the air duct. An external air vent structure is not conducive to installation and transportation, and long-term jolts may lead to looseness of screws.